Ventilation of dynamo-electric machines



, June 3,1930. E. H. FREIBURGHOUSE' 1,761,733

VENTILATION OF DYNAMO ELECTRIC MACHINES Filed Dec. 18, 1928 Fgl.

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Edward H Frelburghouse,

HtsAttor-ney.

Patented June 3, 1930 UNITED STATES PATENT OFFIE EDWARD H. FREIBURGHOUSE, OF SGHENECTADY, NEW YORK, ASSIGNOR T0 GENERAL ELECTRIC COMPANY, A CORPORATION 03 NET/V YORK VENTILATION OF DYNAMIC-ELECTRIC MACHINES,

Application filed December 18, 1928. Serial No. 326,875.

My invention relates to the ventilation of dynamo electric machines of the type comprising a rotatable member and a stationary member having an air inlet opening in the end wall thereof and an air intake casing sur rounding the air inlet opening so that air flows therein to the openingand thence outwardly to a fan which discharges the same into the interior of the stationary member through which it is circulated to cool the machine.

In machines of this character the air flowing from the intake casing to the fan necessarily undergoes a reversal in the direction of flow and in machines as constructed heretofore this has produced considerable turbulence or eddying of the air at the intake ofthe fan so that the velocity head losses of the air entering the fan was very large.

The object of my invention is to provide an air directing member in a machine of this kind which will facilitate the reversal of flow of air passing from the intake casing to the entrance of the fan and also minimize the eddying of air undergoing this change in direction of flow so as to substantially decrease the velocity head losses in air entering the fan. I accomplish this object by providing an air directing member having a curved surface extending from the end wall of the stainvention, and Fig. 3 is an enlarged longitudinal sectional view'of a portion of my im proved air directing member in its relation to the fan employed for ventilating the machine.

For convenience in illustration '1 have shown my invention in the drawing in cellnect-ion with a turbo-generator having a stationary member 10 in which is arranged a rotatable member 11 supported on bearing pedestals 12. The stationary member comprises a core structure 13 having armature windings 14 arranged therein-and the rotatable member is provided with a field exciting winding 15 which is energized. in the usual manner. Although I have shown only one end of the machine it will be understood that the other end thereof is of substantially the same con struction. The stationary member 16 is closed by an inner end shield 16 which constitutes the end wall of the stationary memher. The end shield 16 is provided with an air inlet cpening 17 about the rotatable member 11 through which air flows into the machine, and an outer end shield 18, which is secured to the stationary member, is spaced from the end shield. 16 to form an air intake casing between them. The end shield 18 is provided with acentral opening 19 about the rotatable member having a packing ring 20 therein to prevent the leakage of air from the end shield and is formed with an air inlet opening 19' between the bearing pedestal and the stationary member of the machine. In accordance with the usual practice air is circulated through the machine by a fan secured to the rotatable member which comprises shrouds 21 and 30 spaced apart and having blades 22 secured between them extending axially of the rotatable member, the shroud 30 being bolted directly to the rotatable member.

In the operation of the machine air flows into the intake casing between the end shields 16 and 18 and flows radially toward the rotatable member to the opening 1? from whence it is discharged by the blades 22 of the fan outwardly inside of the end shield 16 as indicated by the arrows in Figs. 1 and 3. It will be observed that this involves a reversal in the direction of flow of air from a direction radially toward the rotatable member to a direction radially outward therefrom. As aresult the turbulence or eddying of the air at the entrance of the fan causes a large loss in velocity head.

In accordance with my invention, therelorc, I provide an air directing member having a curved surface extending from the inner end shield to the machine adjacent the inner periphery of the fan for minimizing the eddying of airflowiiig from the intake casing thereto. One such air directing mem ber considerably reduces the turbulence or eddying of air at the entrance of the fan, but I prefer to employ two such members spaced apartso as to form an air duct in which the direction oi flow of the air is reversed and directed into the fan with a small loss in velocity head. In the particular construction illustrated these air directing members comprise curred annular members 23 and 24 which are spaced apart to form an annular air duct, one end of which opens outwardly into the intake casing and the other end of which opens outwardly into the fan 22. The

member 23 terminates in an edge 23 presented outwardly in the air intake casing and is curved at 23 so that it terminates in an edge 23 presented outwardly in radial alignment with the inner periphery of the shroud 21. The member 2% terminates in an edge 24% which is also presented outwardly in the air intake casing and is curved at 248 so that its inner periphery terminates in an outwarilly presented edge ar adjacent the blades 22 of the fan. The curved air d recting members 23 and an are spaced apart at their outer periphery by guide vanes 25 and are spaced apart at their inner periphcry by guide vanes 26, the guide vanes and 26 being welded or otherwise secured to the air directing members so as to form a rigid construction. The air directing memhers are secured in the opening 17 in the inner end shield 16 of the machine by a plurality of bolts 27 extending through the guide vanes By this construction it will be seen that a large proportion of the air flowing into the fan will be drawn through the duct termed between the air directing members 23 and 2 1 so as to minimize turbulence in the air flowing to the fan, and that the inner curved surface of the member will also considerably reduce the turbulence o1 air flowing centrally there through to the fan.

The fan 22 discharges outwardly into the end shield 16 through an air directing ring 28 which is supported in spaced relation to the inside of the shield 16 by vanes 29, the air directing ring terminating at the periphery of the shroud 30 oi the fan adjacent the rotatable member. In order to prevent leakage of air from the fan at the intake and discharge thereof I arrange a sealing ring 31 about the outer periphery of the shroud 21 having grooves 82 on its inner periphery. The shroud 21 is termed with grooves 33 and 31 which cooperate at its inner periphery with grooves 82 of the sealing ring and the edge 23 of the air directing member 23 to prevent lea l e of air from the fan between them and ti e outer periphery of the shroud 30 of the fan is formed with grooves 35 which also cooperate with the inner periphery of the air drecting ring 28 to prevent leakage of air rom the tan.

In view of the foregoing it will be seen that I have provi ed an air directing arrangement for dyi: 11110 electric machines of the character described which substantially reduces the velocity head losses in the air entering the fan and which also prevents leakage of air from the fan during its operation.

ltloditications o1 th air direction construction which I have described will occur to those skilled in the art so that I do not desire my invention to be limited to the particular arrangement set forth except as defined in the appended claims WVhat I claim as new and desire to secure by Letters Patent of the Unit-ed States, is:

1. An enclosed dynamo-electric machine comprising stationary and rotatable members, the end wall of said stationary member having an air inlet opening about said rotatable member, an air intake casing surrounding said air inlet opening, a fan carried by said rotatable member and arranged adjacent said opening, said tan having a shroud spaced axially from said rotatable member and blades arrai'lgcd between them for delivering air oiiitwardly from said rotatable member into said stationary member, and an air director including a plurality of annular curved members, guide vanes spacing said members apart ant bolts extending through said guide vanes :ior securing said curved members to the end wall of said stationary member about the opening therein, said curved member having edges presented outwardly in said casing to take in air flowing toward the opening in the end wall of said stationary member and having edges presented outwardly in said fan so that air will be directed from said intake casing outwardly into said fan and thereby minimize eddying of air flowing thereto.

2. An enclosed dynamo-electric machine comprising stationary and rotatable members, the end wall of said stationary member having an air inlet opening about said rotatable member, an air intake casing surrounding said air inlet opening, a fan carried by said rotatable member and arranged adjacent said opening, said fan having a shroud spaced axially from said rotatable member and blades arranged between them for delivering air outwardly from said rotatable member into said stationary member, an air director including a plurality of annular curved members, guide vanes spacing said members apart and bolts extending through said guide vanes for securing said n T at curved members to the end wall of said stationary member about the opening therein, and a sealing ring attached to said curved members and surrounding the shroud of said tan, said curved members having edges presented outwardly in said casing to take in air flowing toward the opening in said stationary member and having edges presented outwardly in said fan to direct air thereto and thereby minimize eddying of air flowing thereto.

3. An enclosed dynamo-electric machine comprising stationary and rotatable members, the end wall of said stationary member having an air inlet opening, an air intake casing surrounding said air inlet opening, a fan having a shroud spaced axially, from said rotatable member and blades arranged between them for delivering air outwardly in said stationary member, an air director including a plurality of annular curved mem bers, guide vanes spacing said members apart and means for securing said members to the end wall of said stationary member about the opening therein, and a sealing ring attached to said curved members and surrounding a shroud of said fan, said curved members having edges presented outwardly in said casing to take in air flowing toward the opening in said stationary member and having edges presented outwardly in said fan, one of which is in alignment with the inner periphery of said shroud and the other of which is adjacent the blades of said fan so as to di rect air thereto and thereby minimize the eddying of air flowing thereto, said sealing ring having a grooved inner periphery and said shroud having a grooved inner and outer periphery cooperating with said sealing ring and the edge of said curved member to prevent leakage of air from said fan.

In witness whereof, I have hereunto set my hand this 17th day of December, 1928.

EDWARD H. FREIBURGHOUSE. 

